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        // promise本身是同步的
        // 但是then是异步的





        const p = new Promise((resolve, reject) => {
            console.log(1);
            resolve(3);
        })

        setTimeout(() => {
            console.log(4);
        })

        p.then(res => {
            console.log(res);
        })


        console.log(2);

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